Adsorption of Gas-Phase Nitric Acid to<i>n</i>-Hexane Soot: Thermodynamics and Mechanism
Bibliographic record
Abstract
The adsorption of gas-phase nitric acid on n -hexane soot was measured as a function of temperature, relative humidity (RH), and nitric acid partial pressure in a coated-wall flow tube coupled to an electron-impact mass spectrometer. The specific surface area (SSA) of the soot, determined from the BET isotherm of Kr at 77 K for each sample, was 88−372 times larger than the geometric surface area. The SSA increased linearly with soot mass for thin samples but saturated at high mass. For the most part, the nitric acid adsorption was reversible in the submonolayer regime, and no indication of HONO formation was observed. The uptake increased with decreasing temperature and, for surface coverages between 10 12 and 10 13 molecules cm -2, the average enthalpy of adsorption was −55.8 ± 7.7 kJ mol -1 . A Langmuir−Freundlich model with the heterogeneity parameter equal to 0.5 closely describes the uptake data, implying either that the surface sites are energetically heterogeneous or that nitric acid is dissociating on the surface. The nitric acid adsorption isotherms were independent of relative humidity up to 80% RH at 243 K. Exposure to ppm levels of ozone for about 1 h had no effect on the adsorption. The atmospheric implications of this work are discussed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".